Determining the level of subpopulations of peripheral blood lymphocytes for the diagnosis of chronic renal allograft rejection

Background. One of the main causes of renal allografts (RA) failure in the long-term period after transplantation is progressive chronic allograft dysfunction (CAD), the cause of which in 20 to 60 % of cases is chronic rejection (CR). Diagnosis of the causes of graft dysfunction is based on a morphological study, which has several disadvantages through invasiveness. Therefore, of great interest is the search for non-invasive methods for diagnosing the state of RA, in particular, the study of the cellular link of the immune response. To this end, we decided to investigate the relative number of subpopulations of peripheral blood lymphocytes and their ratio in recipients in the long-term period after kidney transplantation and to assess the informative value of these parameters for the diagnosis of CR RA. Materials and methods. The levels of lymphocyte subpopulations (T-cells, T-helpers, T-cytotoxic, T-activated, ­T-NK-cells, B-cells, NK-cells) were studied in 43 RA recipients depending on the course of the long-term postoperative period and allograft state 1–9 years after transplantation, who were divided into two groups depending on the morphological verification of the diagnosis. Group 1 — 23 patients with satisfactory RA function without signs of rejection; group 2 — 20 patients with CAD caused by a CR according to a puncture biopsy. The control group consisted of 23 healthy donors, whose parameters made up the reference corridor. Results. The analysis showed an increase in the average levels of T-activated lymphocytes in the groups 1 and 2 relative to the control one (8.9 ± 2.0, 8.4 ± 2.4, 6.8 ± 2.1, respectively). There was also a decrease in the mean levels of T-NK cells (2.4 ± 2.0) and B-cells (9.6 ± 2.0) in group 2 as compared to indicators of group 1 (5.6 ± 1.8 and 12.4 ± 2.4, respectively). Analysis of the correlation between specific subpopulation units of lymphocytes showed a statistically significant difference between the T-cell/T-NK-cell index (22.53 vs. 46.89 in the groups 1 and 2, respectively, p < 0.05) and the index of T-activated/β-cell (1.14 vs 4.17 in the groups 1 and 2, respectively, p < 0.05). The sensitivity of the T-cell/T-NK-cell index was 70 %, and the specificity — 60 %. The sensitivity of the T-activated/B-cell index was 55 %, the specificity — 50 %. Conclusions. The decrease in the level of T-NK-cells closer to the lower threshold value of the reference corridor and, accordingly, the ratio of T-cells/T-NK-cells within 44.49–49.29 (46.89 ± 2.40) in the long-term post-transplant period can be an additional sign of a chronic rejection reaction as a cause of progressive renal allograft dysfunction